Hello there! I have an empty 75 gallon tank that I want to setup for dwarf puffers. I would love everyone's recommendations for lighting, filtration, substrate, etc. I have had GSP's, but that was years ago and brackish water. I would also prefer to cycle without having to sacrifice a fish...
I would LOVE everyone's opinions and thoughts on what is best for these little guys. Thanks in advance.

Hey, welcome! In terms of lighting, it's more dependent on what plants you have than the puffers, as they're fine with most options. As for filtration, definitely use either multiple weaker filters or a sponge filter, as the filter needed to suffice in a 75g could possible suck in a dwarf puffer. Substrate isn't terribly important... most people use sand, but I prefer gravel since it's easier for snails to move around on. And as far as cycling, you don't have to sacrifice a fish at all, there are many effective methods to use. Good luck!

You can get away with a bare bottom tank and new species with deceiving false bottoms and some aged driftwoood.
A simple layout of flat rocks and other good looking chunks
They shade the reflection from lights and bare glass.
An outflow pipe or pump aimed in the right area can keep a large amount of the bottom clean of sitting leftovers.

Place some flat rocks on top of old suction cups to create gaps under the rocks for flow as well as keep them stuck down.

In this kind of set-up you can gauge how much stuff is accumulating on the bottom vs. time in your new puffer tanks.
Add substrate and plants as time goes on.

It's amazing how much stuff comes out of plecos and puffers.

The biggest tip for me is to feed almost all puffers food chunks that fit in their mouth ( frozen thawed chunk food).
Old scissors are great.

Countless feeding attempts with puffers and big chunks just made a mess leaving bits scattered.
At least the food goes in the puffers and converts to a brown thing that breaks up in most filters.
Not much for bottom feeding friends left in the puffer tanks either.
Farlowella cats do fairly well on the dark driftwood with the dwarves.